First language acquisition is a hallmark of normative human development. A substantial body of research suggests that language learning is facilitated by the ability to track statistical regularities in linguistic input. Research during the current project period clearly demonstrates that infants are powerful statistical learners. However, the relevance of these abilities to the learning problems presented in infants'linguistic environments remains poorly understood. The research proposed in this application will test specific hypotheses concerning infant statistical language learning, focusing on how infants make use of statistical information. Specific Aim One is to determine which surface statistics infants can use given natural language input. Specific Aim Two is to determine how the statistics of sound sequences in real speech influence word learning. Specific Aim Three is to determine whether infants'on-line language processing is affected by statistical information. The results of the research proposed in this competing continuation application will promote positive developmental outcomes by expanding our understanding of the learning mechanisms underlying normative development. Individuals who are less facile at statistical learning may be at risk for developmental language disorders. Subsequent research will use the outcome of these studies to motivate investigations including populations of young children at risk for atypical language development. PUBLIC HEALTH RELEVANCE: These studies, which are focused on typical language development, provide an opportunity to test targeted hypotheses concerning the mechanisms underlying positive language acquisition outcomes. The results will inform subsequent studies of children at risk for atypical language development, a major public health concern. We are currently working with a number of relevant populations who are potential targets of future studies based on the experiments proposed in this application, including children with Specific Language Impairment (with Dr. Julia Evans, San Diego State University), deaf toddlers who use cochlear implants (with Dr. Ruth Litovsky, UW-Madison and Dr. Tina Grieco-Calub, Northern Illinois University), toddlers who are late-talkers (with Dr. Susan Ellis-Weismer, UW-Madison), children living in poverty (with Drs. Jan Edwards and Julie Washington, UW-Madison), toddlers with Williams Syndrome (with Drs. Carolyn Mervis and Cara Cashon, U. of Lousiville), and children with Cerebral Palsy (with Dr. Katie Hustad, UW-Madison).